The seedlings reached about 4" under the CFL, so I switched to a 400W MH conversion today on an 18/6 schedule. As soon as I did, the RH went down to 20% and the temperature up to over 90deg F. This does not seem good for my plants. Is there any way to cool and humidify the grow space? Using a 1m x 1m x 2m mylar grow tent with the bulb/reflector about 4' from the seedlings. The exhaust fan is already on max. Also cracked a window and turned down the AC (caveat: lower RH), to little avail. Any advice?
I'd try air cooling your lights. It's not clear how far your new mh lamp is from your canopy, but if it's still 4" away like your cfl's, that's way too close. To raise your humidity, you could go to a local drug store and get one of those Vicks vapor humidifiers and not use vicks scent pads in it. Just water... or buy a small humidifier from home depot or wal-mart. Vicks Humidifiers
How do I air cool the lights? No matter what I do with extra ventilation, the temperature is still around 90-100deg F when the light is on and now the RH is about 0% (I've yet to pick up a humidifier). The reflector is over 4' (not 4") from the seedlings. Still, I'm worried these crazy temps are going to kill the plants. Please help!
what kind of reflector do you have for your MH bulb. where is your ballast located, will help slightly if you can have it outside your tent. if you buy an air cooled hood youll just need some ducting and a blower and it will make a tremendous difference. take a look at my grow to get an idea how it works.
Does your reflector have the opening to pull air from there? It should be round if it does, and if it does I would suggest you going with the setup like a dryer has, with a fan pulling the hot air from there into another room. And another fan blowing cool air in about the heighth between the plants and your lights. Remember hot air rises and cool air falls. Also do you have a glass lens that attaches into your reflector at the botom?? If you don't have the glass lens or the opening for ventilation I would suggest upgrading your reflector. If it does I would go as earlier suggested and upgrade your fans.
Also I looked at your humidity problem and couldn't answered it so I did a little research for you. Check out this link bro.... How to Increase Humidity for Indoor Plants | eHow.com
Thanks for the help. I'm using one of those budget MaxWing Reflectors. Should I switch to something like the Euro Reflector? It seems like the cheapest option w/ a glass lens and flange for exhaust.
If the size and design suites your growroom I would definately upgrade! The glass lens and exhaust will allow you to move it closer to your plants as well. So it will be cooler in the room and your plants will benefit from the extra lumens
Upgraded to the Euro today. Almost immediately, temp went down 20deg and RH went up 20%! Thanks for the help!
Happy to hear that bro! Glad things are working out for you now. Did you go with just the new reflector or did you set up the exhaust too?
Got the reflector and set up ducting & fan for exhaust. Don't even need a humidifier now. I'm sure the good advice of everyone here saved the seedlings. The old set up would definitely have killed them once the reflector was moved closer. It was almost 2 meters away and still caused all those problems!
Well happy to hear everythings working out well now, you should start a journal or something with weekly updates. I just started my first grow, it's only with CFL's. No space for an HID right now. But your stuff is going to be taking off now.